Presenter:

Kazunari Hashimoto(University of Yamanashi)

Authors:

Kazunari Hashimoto(University of Yamanashi)

Gen Tatara(RIKEN)

Chikako Uchiyama(University of Yamanashi)

The spin pumping is a method to generate spin polarized electron current (spin current) in ferromagnet-normal metal junctions, where the spin current is induced by precession of the magnetization in the ferromagnet into the normal metal. A standard model used in analyzing the spin pumping consists of a magnetic quantum dot attached to an electron reservoir. Most of its theoretical studies have been performed in an adiabatic regime, where the precession is sufficiently slow compared to the relaxation time of the dot by tunneling. However, since period of the precession (~10-9sec.) is comparable to or shorter than the relaxation time (~10-8sec.) in actual experiments, it is necessary to study the spin pumping under relaxation (it has been studied with the Markovian approximation in [K. Hashimoto, G. Tatara, and C. Uchiyama, Phys. Rev. B 96, 064439(2017)]). In the short time scale, the correlation time of the reservoir should also be considered to be finite. This requires to analyze electron dynamics beyond the Markovian approximation, since it fails in the short time scale. To this end, we study the electron dynamics in terms of the full counting statistics with the quantum master equation without using the Markovian approximation.